Synthetic stone and process of making it



Patented Aug-.1451! UNITED STATES PATENT OFFICE; I 2.382.154

SYNTHETIC STONE AND PROCESS OF MAKINGIT" Paul W; Jones' and John w. SmLa' Fayette, Ind.,. assignors to Rostone: Corporation, La

Fayette, Ind'.,.a corporation of In NoDrawing- Application September11,1941,

. Serial Noi410,430-

4 Claims. (Cl; 106-118) It is the object 01' our invention to producesynamount of anhydrous. alumino-silicate materialtheticstoneandartificial structural material of -with an alkaline-earthbaseand water,withthe. increased strength, bothagainst compression and solid.materials: all in finely comminuted iori'n; inst flexure. 1 a andsubject the moist mass to moistzheatr to:

Our present application isva continuation-in- 5= produce chemicalreaction and. induratiom. part of our co-pending application Serial No.The proportion of the. anhydrous alumino- 149,274,1lled June 19, 1937.silicate material to the. alumino-silicic acid: ma-- Our new syntheticstone is made mainly of aluterial may vary considerably; Any81110111112101 it. mino-silicic acid material, such asshales, slates,is. helpful, from about 5% (where. the strengthand clays, withanxalkaline=earth base-and water,- ening effect beginsxto be noticeable)usually up to induratedrunder moist heat. To that. extent, about 90% byweight of theamount of the our present invention follows the teachingotU." S. alumino-silicic acid material. But the optimum:

- Patent No. 1,852,672, granted. to Pefler, Harrison, amount, for peakstrength, i'sless than that 90%,

and: Ross on Aprili5; 1932; onwhich patent it is and varies somewhatwiththe particular aluminaan improvement. sillcic acid material used.'I-heoptimum for high.

we have" discovered the; surprising fact that compressive strength isusually with: the amount if in addition to the alumino-silicicacidmaterial of anhydrous alumino-silicate material between we use inthe mixture with the alkaline-earth and 80% byweight' of theamount ofalubase and. the water a relativelysmaller amount mino-silicic acidmaterial; while the-optimum for 01'. anhydrous-alumino-silicatematerial, such as .2 high flexural strength is usually with thatperslag'or'ily-ash, weincrease both the compressive centage between.and. 60%. Taking. both strength and the flexural strength. This-yis the.compressive and flexural strength into account more surprisingbecause-synthetic stone and. artiit is usually found that the:- peakstrength iszwith. ficial structural material made oi anhydrous theamountofanhydrous alumino-silicateematee alumino-silicatemateriaLan'alkaline-earth base, rial. between 25% and 50% by weight of:the and'water, with noalumino-silicic acid materialamount 01'alumino-silicic acidmaterial.v as set forth inUZS. Patent No. 1,942,769,granted The alkaline-earth base is most conveniently to Peil'er and oneof us (Jones) on January lime, either high-calcium or dolomiti'c; andwhile 9, 1934-are weaker, both against compression desirably ofapproximately sufllcientz-amountandi and against ilexure, than: arethose. made of no more for'substantially complete reaction with.alumino-silicic acid material, an alkaline-earth the alumino-silicicacid material-andthe-anhybase, and water; for-that fact would leadone tos a n i e' ri y n prac expect that the addition. of the anhydrous ticevary considerably in amount, from about 10% alumino-silicate materialwould weaken the-prod to about 75% (in terms of. hydrated lime) oitheuct, insteadof strengthening it as it unpredictably combined weightof the alumino-sili'cic acidand: does; anhydrous alumino-silicate.materials; usually By alumino-silicicacid material we. mean with bestresults it it is between 35% and.45%', those naturally occurring.materials, such as. of that combined weight. The approximate: shales,slates, clays; gneiss, and schists, which amount-of lime for 'maximumstrength maybe. contain, at lastinpart, one or-moreof the alu- 40computed by adding: of the weight of the mino-silicic acids, andalsocontain in part water alumino-silicic acidmaterial and. 10% of theof constitution. weight of the anhydrous alumino-sllicate .ma-By.anhydrous alumino-sili'cate material we terial. Jmeanmaterials'which' contain, at leastin part, 7 The water should besuillcientv in amount. to

aluminaand silica in'combination, but which are 5 1 produce thoroughwetting. This is somewhat. in. generally considered as essentiallyhaving no excess 01' the amount required: for reaction; and water intheir molecular constitution; Among is usually equaLtobetween 15% and30% o'f the" thisgroup ofmaterials are various slags, clinker, total.weight of the solid ingredients. The water and: scoriae; and. alsofly-ash, which; is the isdesirably added only afterthezsolidingredients" finely powdered. ash: from the combustion of 60have been. thoroughly comminuted and'mixedin' powdered coal; and alsovarious naturally ocdry 'form'. curring alumino-silicate minerals, likelava and Theprecise optimum proportions of these-in:- pumice andvolcanic ash. gredients vary somewhat with diflerent alumino- Incarrying out'ofirpresent' inven ion.v we mix siliclc acid materials. andfor each such. mate alumino-sllicic acid material and" a smaller rial adetermination by test is necessary it the precise maximum strength isdesired. But although the optimum proportions require tests, ourinvention is not limited to optimum proportions; for a marked andsurprising beneficial effect on both compressive and flexural strengths,and on toughness, is obtained when any amount of essentially anhydrousalumino-silicate material up to about 80% to 90% of the amount ofalumino-silicic acid material used is added to a mixture ofalumino-silicic acid material, an an kaline-earth base, and water inmaking synthetic stone.

, In performing our process, the anhydrous alumino-silicate material (ifnot already sufficiently fine), the alumino-silicic acid material, andthe alkaline-earth base, are ground to desired ilneness, preferably atleast as line as minus 200 mesh to minus 325 mesh per inch; and arethoroughly intermixed, desirably with all ingredients dry. Then the drymixture is thoroughly mixed with the predetermined proportion of water,as in a muller-or a wet pan, until the whole becomes a compact wettedmass in which ther is intimate .particle contact of colloidal orquasi-colloidal character. Then this wet mass is shaped as desired, asin molds, under pressure and/or tamping if desired. Then the shapes (orshaped masses) are subjected to moist heat, conveniently steam underpressure, but without complete drying, until the desired chemicalreaction amon the ingredients is effected. Final complete drying maythen be done, in the air, or in an oven; but ordinarily this is neitherdesired nor necessary. V

Example 1 .In one practical example of our process, parts (by weight) ofshale (here an Indiana knobstone shale) containing alumino-silicic acid,2 parts of fly-ash (here on obtained from the Detroit Edison Company),and 3 parts of hydrated (slaked) lime, all of sufllcient fineness topass through a 200-mesh or even through a 325-mesh screen, arethoroughly mixed while. dry. Then 2 parts of water are added; and thewhole is mixed, in a wet pan or similar machine, to produce a thoroughlywetted quasi-colloidal mass.

This wet mass is now formed into the desired 7 shapes, usually in molds;as by hydraulic pressing under pressures from 1500 to 6000 pounds persquare inch, or by heavy tamping either on the mass itself or on a coverplate laid over it. The shaped mass is now put in an autoclave orindurating chamber; and, if desired after first being exposed to normalroom conditions for several hours (as over night) although that need notbe done, is subjected for about two hours to saturated steam at apressure of about 50 to 125 pounds per square inch, conveniently about'75 pounds. This steam may either be introduced into the induratingchamber from outside, or

be generated in the indurating chamber itself by heating the latter.During this two-hour induration the desired chemical reaction takesplace, and the product reaches practically its full strength and isready for use; although drying after the induration produces somefurther increase in strength.

variations and thewide range of proportions over.

which increased strength is obtained over what v is obtained with thefly-ash left out.

In the tests or Tables A and s, the flguresin the shale, fly-ash, andlimeoolumns are partsby weight. The dry 'materials'were thoroughly mixedby hand; an amount of water was used equal to 20% of the total weight ofthe dry ingredients; and the amount of lime in each case was 50% of theweight of shale-plus 10% of the weight of fly-ash. The damp mixtures-were pressed into the desired shapes at 2500 pounds per square inch ina hydraulic press, to produce v a. 2-inch cubes The product thusobtained is definitely stron er than one similarly made with the ily-ashomitted; by at least 25% and usually more both in compressive strengthand in flexural strength.

Example 2 The process of Example 1 is repeated, save that theproportions are varied to show efiects of such b. barsmeasuring V: x 2 x5 inches.

The cubes and bars were indurated by being subjected for two hours tosaturated steam at a pressure of pounds persquare inch. The 2- inchcubes were used for the compression tests, by crushing in a testingmachine. The bars'were used for the flexure tests, by mounting them witha 4-inch clear span, and computing the flexural strength by the formulain which P=the breaking load l=thespan (4") b=the width (2") d=thethickness /z") Example ,3' i

Example 2 was repeated using Goose Lake clay,

from near Joliet, Illinois, with the results shown in the followingTable C Table 0 I Flexurai Clay Fly-ash Lime Strength 0 so a, e10 100 .s60, 4.305 100 24 60 4,535 100 o 40 3,240 100 1 40 3,375 100 21 40 5,8951,00 42 40 4,725.

Example 4 a p Example 2 was repeated, using a shale obtained from nearStreator, Illinois, and adding an amount of asbestos equal to 4% of thetotal weight of the dry ingredients; with the results shown in thefollowing Tables D and E:

Table D Shale Fly-ash Lime 11255211 Table E Flexural Shale F y' Llmestrengt Example 5 from near Brazil, Indiana, and adding an amount ofasbestos equal to 4% of the total weight of the dry ingredients; withthe results shown in the following Tables F and G, in which the upperand lower parts represent tests made at dif ferent times.

Table F Shale y- Lime 2 55133 Table G Flexural Shale ly' Llme strength100- 40 mo 35 40 4,040 00 30 2O 3:530

In the lower part of each of Tables D, E, F,

the sum of the weights of the shale and the lime.

As Examples 4 and 5 show, other ingredients may be included in additionto the alumino-silicic cid material, the anhydrous alumino-silicateExample 2 is repeated, using a shale obtained and G, the weight of thefly-ash is always 25% of aterial, the alkaline-earth base, and thewater.

In addition, after induration the synthetic stone produced may ifdesired be dried and impregnated, as with ome water-repellent substanceto prevent absorption of moisture, such for instance as oils or waxes,of either mineral or vegetable Origin, or natural or synthetic resins.

But these latter things are incidentals. The. fundamental thing is theadded smaller amount of anhydrous alumino-silicate material to thealumino-silicic acid material, the alkaline-earth base, and the Water. yWe claim as our invention:

1. The method of producing synthetic stone'or artificial structuralmaterial, which consists in mixing alumino-silicic acid material, anamount of anhydrous alumino-silicate material equal to between 5% and'by weight of the amount of alumino-silicic acid material, enoughalkalineearth base to produce reaction, and enough water toproducethorough wetting and form a compact wetted mass, with the solidingredients all finely divided, and subjecting the mixture to indurationunder moist heat.

2. The method of producing synthetic stone or artificial structuralmaterial, which consists in mixin alumino-silicic acid material, anamount of anhydrous alumino-silicate material equal to between 25% and50% by weight of the amount of alumino-silicic acid material, enoughalkallne earth base to produce reaction, and enough water to producethorough wetting and form a compact wetted mass, with the solidingredients all finely divided, and subjecting the mixture to indurationunder moist heat. a

3. A synthetic stone or artificial structural material, comprising acompact mixture, indurated under moist heat, of alumino-silicic acidmaterial, an amount of anhydrous alumino-silicate material equaltobetween 5% and 90% by weight of the amount of alumino-silicic acidmaterial, enough alkaline-earth base to produce reaction, and enoughwater to produce thorough wetting and form a compact wetted mass, withthe solid ingredients all finely divided.

4. A synthetic stone or artificial structural material, comprising acompact mixture, indurated under moist heat, of alumino-silicic acidmaterial, an amount of anhydrous alumino-silicate material equal tobetween 25% and 50% by weight of the amount of alumino-silicic' acidmaterial, enough alkaline-earth base-to produce reaction, and enoughwater to produce thorough wetting andform a compact wetted mass, withthe solid ingredients all finely divided.

- PAUL w. JONES.

'JOHN w. SWEZEY.

